1. Field of the Invention
The present invention relates to a charging apparatus for a robot cleaner and a method thereof by which the robot cleaner can be accurately induced to a power source supplier for battery charging when a battery power source for supplying an operating energy to the robot cleaner drops below a predetermined level.
2. Description of the Prior Art
A conventional robot cleaner for performing a cleaning operation while its battery power source is being automatically charged is illustrated in FIG. 1, which includes a robot cleaner 1, a battery 10 provided at a left upper surface thereof in order to supply an operating electric power source to the robot cleaner 1, electric power source receiving means 120 disposed at a rear surface of the cleaner 1 and electrically connected to the battery 10 for charging the battery 10 the when the voltage of the battery 10 is consumed thereby to cause the same to drop below a predetermined charge level, and electric power source supplying means 130 mounted at a certain wall surface W through the intermediary of a wiring 135 within a cleaning area in order to supply the power to the power source receiving means 120.
The power source supply means 130 includes a power transmission unit 131 for converting a commercial AC power source to a DC voltage of a predetermined level necessary for charging the battery thereby outputting the same to other units, a light emitting unit 132 for emitting an optical signal to induce the cleaner 1 so that the DC voltage output by the power transmission unit 131 can be supplied to the cleaner 1, and a connection 133 for connecting the power source supply means 130 to the cleaner 1 so that the cleaner 1 can be electrically connected to the power transmission unit 131 when the optical signal is output from the light emitting unit 132.
Furthermore, the power source receiving means 120 includes a light receiving unit 121 for receiving the optical signal emitted from the light emitting unit 132 of the power source supply means 130, an electric power receiving unit 122 for receiving the DC voltage supplied through the power transmission unit 131 of the power supply means 130 when the optical signal is received from the light receiving unit 121, and a contact terminal 123 for being electrically connected to the battery 10 via a wiring 125 so that an end portion of the connection 133 at the power source means 130 can be accepted.
In the case of the conventional robot cleaner thus described, when a power source of the battery 10 for supplying an operating energy to the cleaner 1 is consumed thereby to cause the same to drop below a predetermined level in the midst of the cleaning operation or during completion stage of the same, the cleaner stops the cleaning operation and starts to move by itself toward the power source supply means 130 disposed on a wall surface. A control means (not shown) recognizes information of a present position of the cleaner and a position information of the power source supply means.
At this time, the optical signal emitted from the light emitting unit 132 of the power supply means 130 is detected by a light receiving means 121 of the power receiving means 120 provided at a rear surface of the cleaner 1.
The control means, based on the detected signal, so controls that the cleaner 1 direct the cleaner to the power supply means 130.
When the cleaner 1 reaches a place near the light emitting unit 132 by being induced to the power supply means 130 according to the optical signal emitted by the light emitting unit 132, the light receiving unit 121 detects the optical signal output from the light emitting unit 132, and the cleaner 1 approaches the power supply means 130 and the end portion of the connection 133 at the power supply means 130 is received by the contact terminal 123 of the power receiving means 120.
Accordingly, the power supply means 130 and the power receiving means 120 are electrically connected, so that a power source voltage applied from an AC power source input terminal is converted to a DC voltage by the power transmission unit 131, and input to the power receiving unit 122. The DC voltage input to the power receiving unit 122 is applied to the battery 10 via a wiring, thereby causing the battery 10 to start to be charged.
However, in the induction method of the power supply means 130 of the cleaner 1 thus described, because the cleaner 1 moves to the power supply means 130 according to inherent position information, and because the wheels of the cleaner 1 slip or skid according to material characteristic and condition of a floor surface on which the cleaner 1 moves, the information of the present position of the cleaner 1 inevitably varies.
Consequently, the cleaner 1 cannot reach the power supply means 130 of the cleaner accurately, so that, as illustrated in FIG. 2, there occurs an allowance to the left and right sides of an imaginary center 136 when viewed from above, thereby serving to broaden an error area 137, which cause a phenomenon where the optical signal of the light emitting unit 132 cannot be received by the light receiving unit 121.
Accordingly, a problem occurs in that trial and error adjustments are repeated where the cleaner 1 is moved to the left side or to the right side in order for the light receiving unit 121 to detect the optical signal of the light emitting unit 132, thereby causing an induction time to be delayed.
There is another problem in that, in order to accurately induce the cleaner to the power supply means, a separate sensor for position correction should be installed, thereby increasing manufacturing cost according to additional use of a sensor and to complicate the construction thereof.
Furthermore, there is still another problem in that a power transmission unit of the power supply means and a power receiving unit of the power receiving means in a conventional robot cleaner are exposed to the exterior, so that safety of the devices cannot be guaranteed nor can an external appearance of the cleaner be made stylish.